<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8"/>
    <title></title>
    <script type="text/javascript">
        var num = 20;

        //如果num为10，则输出哈哈哈哈哈哈
        if (num == 10) {
            alert("哈哈哈哈哈哈");
        }
    </script>
</head>
<body>

</body>
</html>
